In Pressure Sensitive Tapes and labels manufacture, it is very important to use an adhesive according to the final application to obtain the desired performance. The adhesives formulator has several ways to adjust the final adhesive properties to fulfill those requirements, starting from balancing the composition's formula up to changing some ingredients like Polymers, Tackifiers etc.
Some applications, like packaging, require high shear and cohesive strength to maintain the integrity of the content, but when an automated application system is used, a fast adhesion is very important for productivity.
When tapes and labels are required to perform at different conditions than the room or standardized laboratory conditions, according to specifications for standardized test methods, it is necessary to develop specific evaluations at those mentioned different conditions.
Standardized systems like ASTM, PSTC, among others, describe several standardized analytical techniques to characterize all the adhesive properties, most of them are performed at standardized room conditions of 23° C. and 50% of relative humidity, and others are performed at higher temperatures or higher humidity contents for applications, wherein the adhesive is exposed at such conditions.
Rolling ball tack is a preferred test for adhesion performance of adhesive used in applications like tapes and labels when a fast bonding procedure is going to be used. This evaluation is performed using a metallic ball which rolls at constant speed over the adhesive surface of the tape or label to be evaluated. The impulse of the metallic ball, to reach constant speed, is obtained using a metallic standardized ramp with a constant slope angle, over which the ball rolls to reach the surface of the adhesive in the tape or label. The higher the adhesion performance for the adhesive is, the shorter the metallic ball travel will be, and vice versa. The operation to liberate the ball in the top of the ramp, is made manually by an operator who pushes the trigger of the mechanism which retains the ball.
However, test methods and equipments for this evaluation are just referred to be performed at standardized conditions according to PSTC, ASTM and other standardized evaluation methods.
In other words, it is known that the Pressure Sensitive Adhesives, reduce their tack performance when the room temperature is reduced. Thus, when tapes or labels are going to be applied at temperatures below room temperature, it is very important to know if the adhesive maintains enough adhesion at those temperature conditions, to reach an adequate speed of bonding process.
When Rolling ball tack evaluations need to be performed at reduced temperatures, some adhesive producers develop this evaluation in a specific conditioned room, which is equipped with an adequate cooling system to reach the required reduced temperature, and with dimensions that allow an operator to go inside. The operator must be equipped with special clothes to support frozen temperatures in order to operate the ramp and carry out the evaluation. This is an expensive installation to build and uses a considerable amount of energy to operate at the mentioned low temperatures, which increases the cost of the evaluation. Additionally, cooling the room to the evaluation temperature takes several hours, and thus sometimes just one evaluation can be performed every day.
Adhesive formulators are looking for an evaluation system that allows them to develop the rolling ball tack evaluations at under zero temperatures, in a faster way, with reduced installation investment, lower operation costs and operator risks, maintaining evaluation accuracy and repeatability.
U.S. Pat. No. 8,069,702 describes a measuring apparatus to measure adhesion of a tape. The measuring apparatus includes a base, a supporting plate, a positioning mechanism, and an angle-adjusting mechanism. However, the apparatus described in U.S. Pat. No. 8,069,702 does not disclose a remote trigger as the one described in the present invention.
Proposed herein is a new ramp design that can be triggered remotely, generating the possibility of its use inside a small laboratory chamber that can control room conditions of lower temperature and humidity that are required for the aforementioned evaluations. Said new ramp design eliminates the requirement of an expensive cooling room, with all the peripheral equipment and the requirement that the operator must go inside it to operate the system.